Polarized fuse pin plug



Feb. 7, 1950 p, SCMRA 2,496,413

POLARIZED FUSE PIN PLUG Filed May l0, 1949 /f@ JNVENTOR.

Pfff/' Sew/Mw"- Patented Feb. 7, 1950 UNITED STATES PATENT `OFFICE This invention relates to an electric plug yand more Aparticularly to a novel vplug having a fuse for protecting the Aparticular appliance on which the plug is secured.

It is an object of this invention to provide a polarized fuse plug for attachment -to the cord of an electric appliance in such a manner that the fuse may not be replaced or removed while it is plugged into an electrical outlet or socket.

Another object of this invention is to provide a polarized electrical plug having a removable fuse on the positive side of the line for breaking the circuit to the positive line in the event of a short circuit in a particular appliance. As the fuse is positioned on the positive side of the plug and the casing is of an insulated material, the plug may not be disassembled Where the terminals will contact any line parts 'for short circuiting a line.

Still another object of this invention is to provide an electric plug of the kind to be more particularly described hereinafter which may be readily formed for high production and widespread retail distribution having fuses which may readily be replaced as the occasion arises.

A further object of this invention is to provide an lelectric plug of this kind having a fuse incorporated within the plug structure in such a manner that where an overload is applied to the particular appliance the fuse on the plug will fail before the fuse of the line on which the appliance is connected, in this manner protecting the particular appliance without breaking the main circuit on which other appliances may be connected.

By applying fuse plugs'of this kind on the various Figure 2 is a longitudinal section of the plug shown in Figure 1.

Figure 3 is a transverse section, taken on the line 33 of Figure 2.

Figure 4 is a horizontal, longitudinal section, taken on'the line 4-4 of Figure '1.

Figure 5 is a perspective view of the fuse bearing, conducting prong, removed from .the as- 'sembly.

Figure 6 is a perspective view of the other conducting prong, removed from the assembly.

Figure 7 is a perspective view of the insulating plate for covering the open end of the fuse pin plug.

Referring to the drawings, the numeral I0 designates generally a polarized fuse pin plug, constructed according to an embodiment of this invention. The plug I0 is of a size similar to the size vgenerally employed for conventional household appliances and the like, having an insulated body il which may be formed of rubber, Bakelite or other suitable insulating material. The plug body I I is formed with an upwardly opening recess I2 on the upper side thereof deiining a circumferential wall I4 at the upper open end. An elongated bore or central opening I5 is formed along the length of the body II, extending through the center thereof, opening through the lower end and into the bottom of the recess I'l at the upper end. The bore or passage I5, to-

" gether with the recess I2 are provided for enclosing within the body II, the wires Ii or other circuit connecting means which are adapted to be connected to the prongs, to be described hereinafter. The wires I6 are of the conventional flexible type generally employed in household appliances and the like.

The body Il is further formed with an upwardly opening recess Il on one side thereof, the recess I1 opening through the bottom wall of the recess I2 at the upper end of the body, and being closed at its lower end. The recess il is particularly formed for yenclosing within the body II, the fuse element I8 which is carried by one of the outwardly extending prongs, as the prong I9.

A pair of prongs I9 and 20 are adapted to be connected in the body Il and extend upwardly from the upper open end or recess I2. The prongs I9 and 2i) are formed of brass or other suitable conducting material, in substantially the same manner as the conducting prongs of conventional types of plugs. One of the prongs, as the prong 20, is formed of an elongated strip of metal 2| being substantially rectangular in cross section. The strip 2| is bent at its lower end to provide a short overlying, upwardly extending, strip 22 which is adapted to overlie the lower end of the strip 2l and the extreme upper end of the overlying portion 22 is adapted to be bent at right angles to both the prong 20 and the upwardly extending, overlying lower end 22. The outwardly extending flange 24, on the lower end of the prong 20 is formed with a central threaded recess 25 therein within which a screw 2B is adapted to be engaged for securing one end of the pair of wires I6 to the prong 20. The screw 26 together with the outwardly extending flange or arm 24 constitute a contact member with which the wire IS is adapted to be secured within the body I I.

The reverted lower end of the prong 20, which constitutes the upwardly extending arm 2I and the parallel arm 22 at the lower end thereof are adapted to be securely engaged in a recess or socket 21 formed in the bottom wall of the recess I2. The arm 22 may be resiliently biased outwardly relative to the upwardly extending strip 2I whereby the engagement of the overlying strip and prong within the recess 21 will securely engage the prong 2D in the upper end of the body I I.

The other prong I9 is formed of an elongated strip of metal 28, also substantially rectangular in conguration, but having a cross sectional area or width substantially greater than the cross sectional area or Width of the strip 2 I, of the other prong 20. By providing the prongs I9 and 20 of different cross sectional widths the plug I Il is particularly adapted for engagement in a socket wherein the plug I may be engaged only in a certain manner so that the prong I9 will be engaged in the same opening or receptacle of the socket at all times. The prong I9 is formed for engagement in only one opening of the respective socket so that at all times the wire I6 which will be connected to the prong 20 will always be engaged with the same wire which is connected to the respective contact member, not shown in the drawings, of the respective socket.

The strip 28 is bent upwardly at its extreme lower end to provide an upwardly extending arm 29 which extends upwardly only a short distance from the extreme lower end ofthe prong I9 or strip 28. The upper end of the arm 29 is bent outwardly at right angles to the prong I9, as clearly shown in Figure of the drawings. A pair of upwardly extending arms 39 and 3| are fixed to or formed on the opposite side edges of the outwardly extending iiange 32 defining a fuse receiving socket 34. The socket 34 is particularly adapted for receiving the lower end or ferrule of a small cartridge type fuse, particularly designed for engagement within the plug body II.

The fuse 35, adapted to be engaged in the fuse socket 34 is formed of an elongated tubular and cylindrical transparent body 36 having a ferrule 31 recured on the lower end and a ferrule 38 secured on the upper end. The ferrule 31 closes the lower end of the transparent tubular member 36 and the fusible element 39 extends within the transparent member 36 from the lower ferrule 31 to the upper ferrule 38. The upper ferrule 38 is formed with a central threaded recess 49 therein, within which a screw 4I is adapted to be threadably engaged for securing the other wire of the cord IS to the fuse 35 and the prong I9. With' the fuse 35 engaged in the socket 34, the upper end of the upper ferrule 38 is adapted to be disposed substantially on a horizontal plane with the bottom wall of the recess I2 so that the screw 4I which secures the wire to the upper ferrule 38 will be disposed below the upper edge of the side walls I4, at the upper end of the body II.

An insulated cover plate 42 is adapted to be engaged over the upper open end of the body I I, engaging the upper edges of the side walls I4, about the recess I2. The cover plate 42 is formed of an elongated strip of "Bakelite or other suitable exible material, having an opening 44 at one end thereof through which the prong 20 Is adapted to be engaged and an opening 45 at the other end through which the prong I9 may be slidably engaged. A depending arm or separator plate 46 is iixed on the lower side of the cover plate 42, depending therefrom and positioned adjacent the opening 45, through which the prong I9 is adapted to be extended. The separator plate or wall 46 is adapted to be extended downwardly into the recess I1, within the body II and is particularly designed to be positioned between the upper ferrule 38 of the fuse 35, and the outside surface of the strip 28 of the prong I9. The separator plate 46 is formed of insulating material for suitably insulating the prong I9 from the connection of the wire I6 with the upper end of the fuse 35.

The width of the separator member 48 is slightly less than the distance between the side walls I4 of the body I I, so that the wire I6 may be engaged about one side of the prong I9 and engaged with the screw 4I which is removably engaged with the upper ferrule 38 of the fuse 35. The separator plate 46 will hold the fuse and the wire from engagement with the prong I9 whereby the circuit connection between the prong I9 and the wire I6 must be through the fusible elements 39.

In the use and operation of the plug I0, the different sized prongs I9 and 20 particularly provide for the application of the plug I0 as a polarized plug to be used where the prong I9, which bears the fuse 35, will be connected to the positive side of the circuit. The cover 42 is frictionally engaged about the prongs I9 and 20, the separator plate 42 also being frictionally engaged between the prong I9 and the upper end of the fuse 35 for securing the cover plate 42 in place. For installing a fuse 35 within the plug body II, the cover plate 42 may be slidably removed from the upper end of the prongs I9 and 20 and with the wire attached to the upper ferrule 38, the fuse 35 may be slidably removed from engagement in the resilient socket 34. The screw 4I will then be removed from the upper ferrule 38 for disconnecting the wire IE from the fuse and from the plug IIl. The screw 4I is then engaged in the recess 40 of a new fuse 35 and the wire I 6 is adapted to be engaged between the head of the screw 4I and the upper ferrule 38. With the fuse 35 connected to the wire I6, the lower ferrule 31 is then slidably engaged in the socket member 34 for connecting the fuse and the wire I6 to the positive prong I9.

I do not mean to confine myself to the exact details of construction herein disclosed, but claim all variations falling within the purview of the appended claims.

I claim:

l. A fused electric plug, comprising a body portion formed of electrical insulating material and having a central longitudinal wire receiving opening extending therethrough and provided in its forward face with a relatively shallow transverse recess, the body portion having a side longitudinal fuse receiving recess leading into one end of the shallow recess and extending substantially parallel to the wire receiving opening, a first prong for the plug and extending longitudinally forwardly of the forward face of the body portion and including a lateral extension seated against the bottom of the shallow recess, a iirst terminal screw for connecting the lateral extension of the first prong with the body portion, a first Wire extending through the wire receiving` opening and having its free end disposed within the shallow recess and connected with the rst terminal screw, a second prong for the plug arranged in laterally opposed spaced relation to the first prong and extending into the fuse receiving recess and including a lateral extension seated upon the bottom of the fuse receiving recess, socket means secured to the lateral extension of the second prong, a fuse mounted within the fuse receiving recess and having its inner end connected with the socket means and its outer end disposed adjacent to the bottom of the shallow recess, the outer end of the fuse having a screw threaded opening, a second terminal screw mounted within the screw threaded opening of the fuse, a second wire extending through the wire receiving opening and having its free end arranged within the shallow recess and electrically connected with the second terminal screw, and an insulating plate for covering the shallow recess and having openings for receiving the rst and second prongs, said insulating plate including a longitudinally inwardly extending strip for engagement between the fuse l and second prong to maintain them electrically insulated.

2. A fused electric plug, comprising a body portion formed of insulating material and having a central longitudinal wire receiving opening extending therethrough and provided in its forward face with a relatively shallow transverse recess extending for substantially the entire width of the plug, the body portion having a side longitudinal deep fuse receiving recess arranged substantially parallel to and spaced laterally of the wire receiving opening and leading into the shallow recess adjacent to one end of the same, a first prong for the plug and extending longitudinally forwardly of the forward face of the body portion and including a lateral extension seated against the bottom of the shallow recess near one end of such recess, a rst terminal screw for connecting the lateral extension of the first prong with the body portion, a first wire extending longitudinally through the wire receiving opening and having a forward lateral extension disposed within the shallow recess and connected with the rst terminal screw, a second prong for the plug arranged in opposed laterally spaced relation to the first prong, the second prong being substantially longer than the rst prong and extending into and through substantially the entire length of the deep fuse receiving recess, the second prong including a lateral extension near its inner end and seated upon the bottom of the fuse receiving recess, upstanding laterally spaced socket arms secured to the lateral extension of the second prong and arranged near the bottom of the fuse receiving recess, an elongated longitudinally extending fuse mounted within the fuse receiving recess and having its inner end mounted between the socket arms and in electrical contact therewith, the outer end of the fuse being arranged adjacent to the bottom of the shallow recess and having a screw threaded opening, a second terminal screw mounted within the screw threaded opening of the fuse, a second wire extending through the wire receiving kopening and having a forward lateral extension arranged within the shallow recess and connected with thesecond terminal screw, and a forward insulating cover plate for the shallow recess and having spaced openings to receive the first and second prongs, said insulating plate including a longitudinally inwardly extending strip projecting into the fuse receiving opening and arranged between the fuse and second prong.

PETER SCIARA.

REFERENCES CITED The following references are of record in the 

